On Mon, Dec 27, 2021 at 12:48:05PM +0000, Marc Zyngier wrote:
> Contrary to popular belief, there is no such thing as a default
> IPA size on arm64. Anything goes, and implementations are the
> usual Wild West.
>
> The selftest infrastructure default to 40bit IPA, which obviously
> doesn't work for some systems out there.
>
> Turn VM_MODE_DEFAULT from a constant into a variable, and let
> guest_modes_append_default() populate it, depending on what
> the HW can do. In order to preserve the current behaviour, we
> still pick 40bits IPA as the default if it is available, and
> the largest supported IPA space otherwise.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> .../testing/selftests/kvm/include/kvm_util.h | 4 ++-
> tools/testing/selftests/kvm/lib/guest_modes.c | 30 +++++++++++++++++--
> 2 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 2d62edc49d67..7fa0a93d7526 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -53,7 +53,9 @@ enum vm_guest_mode {
>
> #if defined(__aarch64__)
>
> -#define VM_MODE_DEFAULT VM_MODE_P40V48_4K
> +extern enum vm_guest_mode vm_mode_default;
> +
> +#define VM_MODE_DEFAULT vm_mode_default
> #define MIN_PAGE_SHIFT 12U
> #define ptes_per_page(page_size) ((page_size) / 8)
>
> diff --git a/tools/testing/selftests/kvm/lib/guest_modes.c b/tools/testing/selftests/kvm/lib/guest_modes.c
> index c330f414ef96..5e3fdbd992fd 100644
> --- a/tools/testing/selftests/kvm/lib/guest_modes.c
> +++ b/tools/testing/selftests/kvm/lib/guest_modes.c
> @@ -4,22 +4,46 @@
> */
> #include "guest_modes.h"
>
> +#ifdef __aarch64__
> +enum vm_guest_mode vm_mode_default;
> +#endif
> +
> struct guest_mode guest_modes[NUM_VM_MODES];
>
> void guest_modes_append_default(void)
> {
> +#ifndef __aarch64__
> guest_mode_append(VM_MODE_DEFAULT, true, true);
> -
> -#ifdef __aarch64__
> - guest_mode_append(VM_MODE_P40V48_64K, true, true);
> +#else
> {
> unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
> + int i;
> +
> + vm_mode_default = NUM_VM_MODES;
> +
> if (limit >= 52)
> guest_mode_append(VM_MODE_P52V48_64K, true, true);
> if (limit >= 48) {
> guest_mode_append(VM_MODE_P48V48_4K, true, true);
> guest_mode_append(VM_MODE_P48V48_64K, true, true);
> }
> + if (limit >= 40) {
> + guest_mode_append(VM_MODE_P40V48_4K, true, true);
> + guest_mode_append(VM_MODE_P40V48_64K, true, true);
> + vm_mode_default = VM_MODE_P40V48_4K;
> + }
> +
> + /*
> + * Pick the first supported IPA size if the default
> + * isn't available.
> + */
> + for (i = 0; vm_mode_default == NUM_VM_MODES && i < NUM_VM_MODES; i++) {
> + if (guest_modes[i].supported && guest_modes[i].enabled)
> + vm_mode_default = i;
Since we don't have a 'break' here, this picks the last supported size
(of the guest_modes list), not the first, as the comment implies it should
do.
Thanks,
drew
> + }
> +
> + TEST_ASSERT(vm_mode_default != NUM_VM_MODES,
> + "No supported mode!");
> }
> #endif
> #ifdef __s390x__
> --
> 2.30.2
>
